May 2012 Calendar Update: How to lock past events.

May 2012 Calendar Update: How to lock past events.

How would one lock past events now? In the old system one could simple disable the date field in Edit mode. In the new system the Drag & Drop feature only calls the date field On Update script, so what On Update script would one use to cancel such an attempt to change a past event using the Drag & Drop feature?

UPDATE: To prevent the Drag & Drop from changing dates I put a script at On Update for the Date field which basically changes it back right away to what it was and then refreshes the page...BUT I can't trigger an alert in On Update, so all I could do is add a notice to my html that the Drag & Drop has been disabled and only results in a page refresh....sad.   Does anyone know of a better way to Disable Drag & Drop?

I really think the Drag & Drop feature should call On Edit as a default and then have a setting which enables it to not make that call. This would assure developers the ability to control date changes.